STANFORD — The foundation for conference titles and BCS berths is laid during the second session of Stanford’s spring practice. That’s when the coaching staff turns its focus, almost exclusively, to the most important plays in football: Third down, red zone and short-yardage.

“We don’t ever want to come out here and just run plays,” coach David Shaw said Monday. “We put the base stuff in the first session; the second session is, in my opinion, what wins games.”

The Cardinal will have three key players available for the second session, which began Monday and ends April 13.

Linebacker Shayne Skov, tailback Tyler Gaffney and safety Ed Reynolds rejoined the team this week after missing all or part of the first session for a variety of reasons:

Reynolds, an all-conference safety, is fully recovered from a minor leg injury suffered last month.

Skov is back after being suspended for the winter academic quarter, a punishment that stemmed from his Jan. ’12 on-campus arrest for suspicion of DUI.

Gaffney spent last year playing in the Pittsburgh Pirates organization. He decided in January to return to Stanford to earn his degree and use his final season of football eligibility.

“I’m much more mature,” said Gaffney, who is expected to compete for the starting tailback position with veteran Anthony Wilkerson. “I’ve really hit the film. Before, I would just play.”

Gaffney, who wasn’t enrolled in school during the winter quarter, worked out with Stanford’s NFL Draft prospects. He did offensive and defensive drills in an attempt, he said, to become more “football savvy” after being away from the game.

Asked if Gaffney looked rusty, Shaw said: “It wasn’t noticeable.”

Reserve linebacker Blake Martinez suffered an undisclosed injury during spring break and won’t be available in the second session. Neither will backup quarterback Josh Nunes (arm) or cornerback Barry Browning (shoulder), a potential starter.

The Cardinal and White Spring Game, set for April 13 at Stanford Stadium (3 p.m.), will feature an offense vs. defense format and be televised by the Pac-12 Networks.

Jon Wilner has been covering college sports for decades and is an AP top-25 football and basketball voter as well as a Heisman Trophy voter. He was named Beat Writer of the Year in 2013 by the Football Writers Association of America for his coverage of the Pac-12, won first place for feature writing in 2016 in the Associated Press Sports Editors writing contest and is a five-time APSE honoree.